Technical Field
The present disclosure relates to the field of microencapsulated probiotic bacteria and food or beverage products containing the microencapsulated probiotic bacteria. The microencapsulated probiotic bacteria are encapsulated in microcapsules, each of which comprises a matrix of a gelled alginate. An outer surface of the gelled alginate matrix is coated with a vegetable oil or treated with sodium chloride.
Description of the Related Art
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, is neither expressly nor impliedly admitted as prior art against the present invention.
Probiotic bacteria are live bacterial microbes that beneficially influence the health and nutrition of individuals by promoting a healthier microflora in the host's intestine and inhibiting pathogenic bacteria. Potential mechanisms of the anti-pathogenic effects of probiotic bacteria are through decreasing the luminal pH by the production of short chain fatty acids such as acetic acid, lactic acid or propionic acid, rendering vital nutrients unavailable to pathogens, altering the redox potential of the environment, producing hydrogen peroxide or producing bacteriocins or other inhibitory substances. Probiotic microflora are dependent on substances obtained from the diet of the host organism. Probiotic bacteria typically colonize in the large intestine and can serve either or both of at least two major roles: they can supplement the natural flora of the gastrointestinal tract with additional bacteria, and they can be effective in treating a number of health conditions, including, but not limited to (1) gastrointestinal tract related disorders (e.g., constipation and diarrhea caused by an infection by pathogenic organisms, antibiotics, chemotherapy, etc.); (2) stimulation and modulation of the immune system; (3) anti-tumoral effects resulting from inactivation or inhibition of carcinogenic compounds present in the gastrointestinal tract by reduction of intestinal bacterial enzymatic activities (e.g., O-glucuronidase, azoreductase, nitroreductase, etc.); (4) reduced production of toxic final products (e.g., ammonia, phenols, other protein metabolites known to influence hepatic cirrhosis, etc.); (5) reduction of serum cholesterol and arterial pressure; (6) maintenance of mucosal integrity; (7) alleviation of lactose intolerance symptoms; and/or (8) prevention of vaginitis. Some of the most common types of probiotic bacteria include Lactobacillus and Bifidobacteria.
Probiotic bacteria are sensitive to various environmental conditions such as pH (many desirable probiotics grow best at pH values around 7.0), moisture, elevated temperatures, high concentrations of bile salts (e.g. 0.3% or higher for certain strains of probiotic bacteria), air and light, particularly UV light. When these conditions are not properly controlled, the viability (often measured in colony forming units (CFU), or as metabolic activity rates), and therefore the efficacy of probiotic bacteria can be substantially reduced.
To be used as beneficial and/or therapeutic agents in a diet, probiotic bacteria need to be protected (a) during the manufacturing process, e.g. when probiotic bacteria are supplemented to a food product that is baked or pasteurized at an elevated temperature; (b) during storage, either alone or in a carrier product, e.g. a food, such as fermented milk, e.g. yogurt, soft, semi-hard and hard cheese, ice cream, and frozen fermented dairy desserts; and (c) while passing through the digestive tract, especially the stomach with an acidic pH of about 2 and the intestines with bile salts. In dairy products such as yogurt, probiotic bacteria have to survive mildly acidic conditions (e.g. at a pH of about 4) for an extended period of time. Probiotic bacterial survival in products is affected by a range of factors, including pH, post-acidification (during storage) in fermented products, and storage temperatures. All these stresses result in death of a significant percentage of probiotic bacterial cells. Therefore, the typical standard for food sold with health claims related to probiotic bacteria is the inclusion of at least 109-1010 colony forming units (CFU) of viable probiotic bacteria per serving. The International Dairy Federation (IDF) suggests that a minimum of 107 probiotic bacteria cells should be alive at the time of consumption per gram of the product, in order to achieve the claimed health benefits.
Encapsulation has been used to prevent damage to or degradation of probiotic bacteria during storage, exposure to elevated temperatures, and exposure to acidic and high bile salt environments, for example, when they pass through the gastrointestinal tract, and to increase the stability or viability of the probiotic bacteria. Encapsulation is a process of creating a matrix wholly enveloping a core of encapsulated material, i.e. probiotic bacteria. As a result, the matrix, with its outer surface facing the surrounding environment, provides the encapsulated probiotic bacteria a barrier to the surrounding environment. The matrix usually comprises one or more biopolymers. The matrix may be subsequently degraded to release the probiotic bacteria at a target site, e.g. the small intestine and/or colon. The microcapsules may range from submicron to several microns or larger up to 1000 microns in size, and can be of different shapes.
Several biopolymers, such as alginate, starch, xanthan gum, guar gum, locust bean gum, and carrageenan gum, may be used as matrix materials to protect probiotic bacteria. Refined from brown seaweeds, alginates are natural anionic polysaccharides made up by D-mannuronic and L-guluronic acid residues joined linearly by 1-4 glycosidic linkages. Alginates from different species of brown seaweed often have variations in their chemical structure, resulting in different physical properties. For example, some may yield an alginate that gives a strong gel, while others may yield a weaker gel. Alginates are commonly available as a sodium or potassium salt (i.e., sodium alginate or potassium alginate). Natural alginates may be chemically modified to obtain synthetic alginates with improved biocompatibility and more desirable physiochemical properties, such as alginate polymer stability, pore size, and hydrophobicity/hydrophilicity.
The viscosity of an alginate solution can vary, depending on the alginate concentration, length of the alginate molecules, or the number of monomer units in the chains, or the weight average molecular weight of an alginate polymer (the weight average molecular weight of sodium alginate typically ranges from 10,000 to 600,000 Da), with longer chains resulting in higher viscosities at similar concentrations. For example, a low viscosity sodium alginate available from Sigma Aldrich has a viscosity of 4-12 cP when dissolved in water at a concentration of 1% at 25° C. A medium viscosity sodium alginate available from Sigma Aldrich has a viscosity of no less than 2,000 cP when dissolved in water at a concentration of 2% at 25° C. A high viscosity sodium alginate available from Sigma Aldrich has a viscosity of about 14,000 cP when dissolved in water at a concentration of 2% at 25° C. When alginate is exposed to divalent cations, such as Ca2+, Mg2+, or Fe2+, the alginate undergoes gelation. Alginate encapsulation is used due to its simple preparation, low cost, and good biocompatibility, since alginate does not affect the viability of most types of encapsulated probiotic bacteria. Although alginate encapsulation has shown a protective effect on the viability of different probiotic bacteria subjected to different stress factors, including low pH, bile salts, and storage (when incorporated in foods), the protective effect is mostly partial and inadequate.
Olive oil is a fat obtained from the olive (the fruit of Olea europaea; family Oleaceae), a traditional tree crop of the Mediterranean Basin. The oil is produced by pressing whole olives and is commonly used in cooking, cosmetics, pharmaceuticals, and soaps. Olive oil is composed mainly of the mixed triglyceride esters of oleic acid and palmitic acid and of other fatty acids, along with traces of squalene (up to 0.7%) and sterols (about 0.2% phytosterol and tocosterols).
Canola oil is a widely consumed vegetable oil and key ingredient in many foods. Its reputation as a healthy oil has created high demand in markets around the world. It typically contains about 61% oleic acid, about 21% linoleic acid, about 9-11% alpha-linolenic acid, about 7% saturated fatty acids, about 4% plamitic acid, about 2% stearic acid, and about 0.4% trans fat.
It is an object of this disclosure to provide compositions of microencapsulated probiotic bacteria that are protected from degradation by an acidic aqueous solution, an aqueous solution with a high concentration of bile salts, elevated temperatures, and/or prolonged storage, such that the microencapsulated probiotic bacteria are more viable and/or metabolically active than their non-microencapsulate counterparts.